Excess Lead in the Neural Retina in Age-Related Macular Degeneration
Accepted 1 July 2009. published online 07 September 2009.
Purpose
To measure lead and cadmium in retinal tissues of human donor eyes with and without age-related macular degeneration (AMD).
Design
Laboratory investigation.
Methods
Lead and cadmium concentrations in retinal tissues (neural retina and retinal pigment epithelium [RPE]–choroid complex) in 25 subjects with AMD (50 donor eyes) and 36 normal subjects (72 donor eyes) were determined by using inductively coupled plasma-mass spectrometry. Severity of AMD was graded by using color fundus photographs and the Minnesota Grading System. Differences in metal concentrations were compared by using Wilcoxon rank-sum tests.
Results
The neural retinas of subjects with AMD had increased lead concentrations (median, 12.0 ng/g; 25% to 75% interquartile range, 8 to 18 ng/g; n = 25) compared with normal subjects (median, 8.0 ng/g; 25% to 75% interquartile range, 0 to 11 ng/g; P = .04; n = 36). There was no difference in lead concentration in the RPE–choroid complex between subjects with AMD (median, 198 ng/g; 25% to 75% interquartile range, 87 to 381 ng/g) and normal subjects (median, 172 ng/g; 25% to 75% interquartile range, 100 to 288 ng/g; P = .25). Cadmium concentration in the neural retina (median, 0.9 μg/g; 25% to 75% interquartile range, 0.7 to 1.8 μg/g) and RPE–choroid complex (median, 2.2 μg/g; 25% to 75% interquartile range, 1.8 to 3.7 μg/g) in subjects with AMD was not different from concentrations in the neural retina (median, 0.9 μg/g; 25% to 75% interquartile range, 0.7 to 1.4 μg/g; P = .32) and RPE–choroid complex (median, 1.5 μg/g; 25% to 75% interquartile range, 0.9 to 2.5 μg/g; P = .12) of normal subjects.
Conclusions
AMD is associated with excess lead in the neural retina, and this relationship suggests that metal homeostasis in AMD eyes is different from normal.
aDepartment of Ophthalmology, Mayo Clinic, Rochester, Minnesota
bMetals Laboratory, Mayo Clinic, Rochester, Minnesota
Inquiries to Jay C. Erie, Department of Ophthalmology, 200 1st Street SW, Mayo Clinic, Rochester, MN 55905
ABSTRACT